The present invention relates to the calibration of measurement instruments and, in particular, to the verification of the adjustment.
To make meaningful measurements, it is often necessary to adjust the measurement instruments with verified sources of the parameter of interest. However, having a verified source available for many different values is expensive not only for the sources themselves but also for maintaining the sources in a verified state. In addition, logistical issues arise in trying to manage and access the verified sources.
One approach to this problem is to directly adjust the measurement instrument to just one or, at most, a few verified sources and then, based on knowledge of the internal circuitry and ranges of the instrument, to adjust other values/ranges to “calibration” by comparing them to the adjusted values in the instrument. However, this depends on the assumptions based on this knowledge being true and accurate and staying true and accurate. Without a verified source for each value of interest, it is not certain what the state of verification actually is for an instrument that employs this indirect adjustment.